1. Field of the Invention
The present invention relates to a liquid crystal display module mounting a backlight thereon, and more particularly to a technique which is preferably applicable to a small-sized liquid crystal display module used for a mobile phone or the like.
2. Description of the Related Art
FIG. 10 shows the cross-sectional constitution of an essential part of a conventional liquid crystal display module.
In the conventional liquid crystal display module, a liquid crystal display panel is configured by sandwiching a liquid crystal layer not shown in the drawing between a TFT substrate 11 and a color filter substrate 12 (hereinafter referred to as a CF substrate 12). The TFT substrate 11 is larger than the CF substrate 12 in size. In a region of the TFT substrate 11 which does not overlap with the CF substrate 12, a driver chip 13 which controls driving of the liquid crystal display panel is arranged. An upper polarizer 14 is arranged on the CF substrate 12, and a lower polarizer 21 is also arranged on a lower side of the TFT substrate 11. Further, a backlight is arranged below the liquid crystal display panel thus constituting the liquid crystal display module.
The backlight is constituted of light sources 18 such as LEDs, for example, arranged on a flexible printed circuit board 15 (hereinafter referred to as an FPC 15), and a light guide plate 17 which leads light radiated from the light sources 18 to the whole liquid crystal display panel. An optical sheet 22 is arranged between the light guide plate 17 and the liquid crystal display panel. The optical sheet is formed of, for example, an upper diffusion sheet, an upper prism sheet, a lower prism sheet, a lower diffusion sheet and the like. A reflection sheet 23 is arranged below the light guide plate 17 and plays a role of directing light led to a lower side of the light guide plate 17 toward a liquid crystal display panel side. To satisfy a demand for the reduction of thickness of the liquid crystal display device, the light guide plate 17 is configured to have a small thickness except for a light incident surface which faces the light sources 18. The reason the light incident surface has a large thickness is that, a size of the LED currently preferably used as the light source 18 is larger than a thickness of the light guide plate, and a size of the light incident surface of the light guide plate 17 is increased to conform to the size of the LED. In FIG. 10, numeral 16 indicates a mold frame. The liquid crystal display module is configured by arranging the liquid crystal display panel on an upper side of the frame-shaped mold frame 16 and by arranging the backlight on a lower side of the mold frame 16.
On the FPC 15, in addition to the light sources 18, electronic components (longitudinally-arranged electronic components 19, laterally-arranged electronic components 101, 102) such as capacitors and resistors are mounted. These electronic components (19, 101, 102) are housed in the inside of a recessed housing portion 32 formed in the mold frame 16.
Patent document 1 (JP-A-7-270814) discloses such constitution for housing the electronic components mounted on the FPC 15 in the mold frame 16.